📝  add CPM.Cmake example

Change argument name "subtype" in byte_container_with_subtype

Fix move constructor of json_ref

Add asserts to suppress C28020

Ranged insert test section is added in unit-ordered_json.cpp

Co-authored-by: Niels Lohmann <niels.lohmann@gmail.com>

Fix warnings on older g++ 4.8

declaration of ‘subtype’ shadows a member of 'this'

Update Hedley

Fix and extend documentation of discarded values